780ti is better R9 290x, preformance is close but 290x wastes more power than gtx 480 on full load. Don't know much about the Titan black other than specs, but it is safe to assume it will be as good 780ti or better, but at a 1000 price. I don't recommend getting more than 2 cards in sli or crossfire becuase most games don't scale properly. If you really want to go 4 cards, 4x 780ti is probably your best bet. Also 4x 780 at 2000 is really good value and difference won't be that great.